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Vin help

Discussion in 'Differential & Driveline' started by Marcus, May 5, 2019.

  1. Marcus

    Marcus Full Access Member

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    Have a 1981 GMC Jimmy with the vin ID of 1GTEK18D7BF509290 . Can’t find anything that will decode the vin to find out what gears it has. Not going to pay $20 to get the info from a website. Was hoping to do it the easier way instead of having to take things apart. Any good information would be greatly appreciated!
     
    Wi chevvy guy likes this.
  2. CSFJ

    CSFJ ----------------- Supporting Member

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    There's nothing in the vin that will give you axle ratio. If the rpo codes aren't in the glovebox, or underhood, you'll need to pull a diff cover and get the numbers off of the ring gear.
     
    1987 GMC Jimmy likes this.
  3. Keith Seymore

    Keith Seymore Full Access Member

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    This is absolutely correct.

    K
     
  4. HotRodPC

    HotRodPC Administrator Staff Member

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    Of it's not been changed, the code on the axle tube can tell you. The codes are listed in the Squarebody Library. Best it to always pull the cover, or jack it up, spin the rear tire and count the driveshaft turns.
     
  5. Marcus

    Marcus Full Access Member

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    Okay that’s what I was afraid of. Thanks guys. The glove box is missing all together and nothing under the hood or on the door jam. Gonna have to do it the hard way.
     
  6. yevgenievich

    yevgenievich Full Access Member

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    Mark drive shaft and spin the tire to get a good estimate. If only one rear tire off the ground and open rear then divide the wheel rotation by 2.
     
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  7. HotRodPC

    HotRodPC Administrator Staff Member

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    Exactly, This is just as accurate as pulling the rear cover. There's also a thread in the Diff section for using this method in detail.
     
  8. roundhouse

    roundhouse Full Access Member

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    Always a good idea to pull the cover anyway

    You never know what you’re gonna find

    Usually some loose teeth or something laying in the bottom
     
  9. Marcus

    Marcus Full Access Member

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    Well I know the vehicle and the person who owns it so I know it’s works as well as the front axle. We just don’t know the ratio right now but I will be finding out soon. Trying to get a 3.42 to put in my truck build to make my rear match the front for now. Will be going to switch both out to a 3.73 as soon as I can afford to do it.
     
  10. HotRodPC

    HotRodPC Administrator Staff Member

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    How soon are you looking to do this? Is the truck broke down now? Have you considered a 3/4 ton axle upgrade? I may have a 14 bolt Semi Float for sale sometime this summer with 3.42's in it. You'd have to use a combo U joint, acquire 8 lug wheels and tires and convert your front rotors and hubs to 8 lug. There is no such thing as a factory 14b Full Float in 3.42's, but there is in 3.73. Maybe more of a worthy conversion when you go to 3.73's. Maybe even find a set of 3/4 ton 3.73 axles.
     
  11. Marcus

    Marcus Full Access Member

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    I don’t want 3/4 ton axles. I appreciate it though. I’m getting it ready to drive daily for now. Eventually I’m going to restore it to somewhat factory and make it look good. It was my grandpas truck and then my uncles high school truck so it’s something special. Wanna keep it as close to factory as possible. Just want better gears.
     
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  12. Marcus

    Marcus Full Access Member

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    The rear end is stamped GM9 on drivers side. Stamped 9969 on passenger side. 06LT on passenger side up top.
     
  13. Marcus

    Marcus Full Access Member

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    Ring gear has 4018121 12 41 1280 on it. This means 3.42 right?
     
  14. yevgenievich

    yevgenievich Full Access Member

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    Yes
     
  15. Marcus

    Marcus Full Access Member

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    Thank you. Just wanted to double check with a few people before I went ahead
     

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